Study On Reaction Bonded TiB₂ Based Composite Cathode Materials For Electrolytic Aluminum

Titanium boride(TiB2)ceramics can be used as cathode material for aluminum electrolytic cell because of its excellent electrical conductivity and non-reaction with aluminum(Al)liquid and cryolite.However,due to the lack of high-performance,simple process and low-cost technology for preparing TiB2 ceramics,TiB2 ceramic materials have not been applied in the cathode of industrial aluminum electrolytic cell.In view of this problem,this paper,based on the vacuum melt infiltration Si method,has developed a new technology for the preparation of TiB2 composite material with simple process,low cost and stable performance.Paper based on the vacuum melt infiltration Si prepared TiB2 composite materials with better conductive properties,and the introduction of strengthening phase SiC and MoSi2 in the composites,raw material TiB2 particle size distribution and optimization of C content in the raw materials to reduce free Si content in composite materials,discusses the influence of the strengthening phase type,grain size distribution and C content in raw materials for TiB2 composite phase,microstructure,volume density,resistivity,and the electrolytic aluminum erosion resistance.The research work will be of great significance for the promotion and application of TiB2 ceramics in electrolytic aluminum industry.Firstly,TiB2-SiC,TiB2-MoSi2 and TiB2-SiC-MoSi2 inert cathode materials with uniform and dense tissue can be prepared by vacuum melting and infiltration Si at 1600?.The results show that the relative density can reach above 97.8%,and the resistivity is better than the national standard of electrolytic aluminum industry.Through laboratory electrolysis experiments show that the SiC as strengthening phase,TiB2 composite material of aluminum corrosion resistance is best,the corrosion rate is 0.125 mm/h,erosion layer of Al content is 7.74 at.%,in the process of electrolysis,composite cathode material residual Si and MoSi2 solubility in Al reaction is the main reason for the material in the process of electrochemical erosion.Secondly,based on the particle dense accumulation theory,the effect of TiB2 powder particle size distribution on the microstructure and properties of TiB2-SiC composite cathode materials was studied.The results show that:when the coarse particles(104 ?m):medium particles(25 ?m):fine particles(3?m)of TiB2 is 3:3:14,compaction density of powder is biggest,2.26 g/cm3,the relative density of green body is biggest,62.4%,the residual Si contents of TiB2-SiC composites after infiltrating Si can reduce to 19.7 vol.%.Composite materials have best electrolytic aluminium corrosion resistance,the corrosion rate is 0.095 mm/h,the Al content in the erosion layer was 4.32 at.%.Finally,the effect of the raw material C content on the microstructure and properties of TiB2-SiC composite cathode materials was studied.The results show that:along with the increase of the content of raw material C,TiB2-SiC composite cathode material resistivity increases gradually,residual Si content decreases.When the content of raw material C is 25 wt.%,the microstructure of the composite material is uniform and dense,and the residual Si content in the composite material can be reduced to 14.4 vol.%,the electrolytic aluminum composite has the best corrosion resistance,with the corrosion rate of 0.09 mm/h and the Al content in the erosion layer of 4.09 at.%.